Influence of NbC particles on microstructure and wear properties of AlCoCrFeNi2.1 eutectic high-entropy alloy coatings prepared by laser cladding

The AlCoCrFeNi2.1 eutectic high-entropy alloy (EHEA) coating obtained optimal laser cladding parameters by temperature field simulation and experimental comparison, and the AlCoCrFeNi2.1-xNbC (x = 0, 2.5, 5.0, 7.5, 10 wt%) composite coatings were successfully prepared using laser cladding. The effect of NbC content on the microstructure, Vickers hardness, and wear resistance of AlCoCrFeNi2.1-xNbC composite coatings were systematically investigated. The coatings are composed of NbC, FCC/Ll2, and BCC phases. With the addition of NbC particle, the volume fraction of the NbC phase increases, and their morphology gradually transforms from rod- shaped to irregular polyhedral. The hardness value of the AlCoCrFeNi2.1-xNbC composite coatings increased from 270 HV0.5 to 365 HV0.5 (hardness value equivalent to H13 steel matrix 2 times). The average friction coefficient and wear volume of AlCoCrFeNi2.1-xNbC composite coatings have significantly decreased. The AlCoCrFeNi2.1-5.0NbC composite coating exhibited the optimal wear resistance with a friction coefficient and wear volume of 0.59 and 3.96 x 106 mu m3, respectively. While the friction coefficient and wear volume of the H13 are 1.0 and 2.05 x 107 mu m3. This was attributed to the suitable proportion of NbC particles that made the coating form a uniform microstructure with appropriate hard and wear resistant.